Radial pipe reactor

ABSTRACT

An arrangement for addition of chlorine dioxide to flowing water in a pipeline is provided. The reactants are reacted in a reaction chamber located in the flow of water and the chlorine dioxide is passed from the reaction chamber directly into the flowing water.

The invention relates to an arrangement for the addition of chlorinedioxide to a water-carrying pipeline, comprising a cylindrical reactionchamber and two reactant lines which open out into the reaction chamberand via which two reactants can be conveyed separately, from outside thepipeline, into the reaction chamber, the reaction chamber being providedwith an exit hole which allows the exit of chlorine dioxide, formed fromthe reactants in the reaction chamber, into the water carried by thepipeline, and the axis of the exit hole in the service state beingoriented in the direction of the longitudinal axis of the pipeline.

An arrangement of this kind is known from U.S. Pat. No. 4,534,952.

Water for industrial and commercial use must be treated so that it isdisinfected thoroughly, safely and in an environmental benign way.Cooling or process waters offer ideal conditions for the multiplicationof microorganisms, for example. Slime-forming bacteria in particularform so-called biofilms, which are microbiological contaminations which,in cooling water lines, severely disrupt heat transfer and causecorrosion.

A particularly efficient agent for water disinfection on account of itsactivity against microorganisms is chlorine dioxide (ClO₂). It is activeacross a broad pH range and can be used not only to treat industrialwaters such as cooling or process waters, in particular, but can also beused—subject to compliance with appropriately low concentration—in thebeverage and food industries as well, in agriculture or in medicaltechnology. A further field of application is in the paper industry,where chlorine dioxide is used to bleach pulp. Lastly, chlorine dioxidealso serves for the disinfection of swimming pool water.

The commercial units typical to date for producing chlorine dioxidecontain considerable quantities of chlorine dioxide, with all of theattendant risks in the operation of the generating units. The riskderives from the fact that chlorine dioxide is a highly toxic, explosivechemical, which even at low concentrations undergoes explosivedecomposition and, in so doing, releases chlorine.

On account of its hazardous nature and low stability, ClO₂ is nothappily transported or stored, being instead, more preferably,synthesized directly at the site of use, more particularly in the waterthat is to be treated. In this way, the problem of producing andhandling toxic and explosive chlorine dioxide is resolved. Accordingly,a variety of patent specifications disclose chlorine dioxide reactorswhich generate the ClO₂ in situ and supply it immediately to the waterto be treated, without further temporary storage. Examples of this kindare found in WO2009/077309, WO2009/077160A1, DE202004005755U1,US2005/0244328A1 and U.S. Pat. No. 4,534,952.

Generation of chlorine dioxide (ClO₂) in situ takes place popularly bythe chlorite/hydrochloric acid process, in which hydrochloric acid (HCl)is reacted with sodium chlorite (NaClO₂) to give ClO₂, water (H₂O) andsodium chloride (NaCl):

5NaClO₂+4HCl->4ClO₂+5NaCl+2H₂O

An advantage of this process is that there are only two reactants to beconveyed into the reactor, namely hydrochloric acid (HCl) with sodiumchlorite (NaClO₂). Since both chemicals are in aqueous solution, this istechnically no problem, apart from the corrosiveness of these media.Mixed in a reactor, the two reactants undergo immediate and vigorousreaction to give the desired chlorine dioxide (ClO₂). The water (H₂O) ofreaction that is formed, and the water constituents of the reactantssupplied in aqueous form, wash the chlorine dioxide in highlyconcentrated aqueous solution from the reactor, where it becomes dilutedwith the water to be treated, attaining less hazardous but stillbiocidal concentrations. A disadvantage of this process is theinevitable formation of sodium chloride (NaCl), which if the solubilitylimit is exceeded, precipitates in crystalline form and clogs thereactor.

Many reactors known in the patent literature for the generation ofchlorine dioxide in situ within the water to be treated are arrangedwithin pipelines which carry the water to be treated. Reactors to bementioned here include, first of all, those which have a tubularreaction chamber, which extends essentially along the pipeline with thewater to be treated, and said water flowing around the reactor. Oneexample of an axial reactor of this kind is found in DE20200400575501.Another example is shown in DE102010027908A1. With these chlorinedioxide reactors, then, the tubular reaction chamber extends along thepipe and discharges the synthesized chlorine dioxide at the distal endof the reactor through an exit opening which is directed in thelongitudinal direction of the pipe, in other words in the flow directionof the water to be treated. With axial pipe reactors of this kind, thesupplying of the reactants proves to be difficult.

U.S. Pat. No. 4,534,952 discloses a pipe reactor for generating chlorinedioxide, which is arranged in a bend in the pipeline with the water tobe treated. In the region where the product exits, the reaction chamberextends likewise axially in the flow direction. Since the shaft runsradially, so to speak, at least sectionally, in the region of the bendin the pipe, the supplying of the reactants into the reaction chamber iseasier. A disadvantage of this embodiment is that there are sections ofthe reaction chamber where ambient air, rather than the water to betreated, flows around the reaction chamber, since the two reactants arestill mixed outside the pipeline. This means that in an accidentscenario, toxic chlorine dioxide may be released. A construction of thiskind is therefore inadvisable on safety grounds.

Known from German published specification DE1203691 is a chlorinedioxide synthesis reactor whose reaction chamber is implemented in theform of a dead water zone on the pipeline. Extending into the dead waterzone are two open reactant lines via which the reactants are meteredinto the dead water for the purpose of synthesizing the chlorinedioxide. Within the dead water, the reactants undergo reaction to formchlorine dioxide, which exits from the dead water zone and is entrainedby the drinking water to be treated, which flows in through thepipeline. This embodiment appears unfavourable from the standpoint offluid dynamics. Moreover, there is a risk of the base of the dead waterzone increasingly salting up. Lastly, the reactant lines run radially,unprotected, through the pipeline.

In light of this prior art, the object on which the present invention isbased is that of specifying an arrangement for the synthesis of chlorinedioxide in situ within a pipeline that carries the water to be treated,this arrangement exhibiting high operational reliability and propertiesthat are favourable from the standpoint of fluid dynamics.

This object is achieved, surprisingly, in that the reaction chamber isarranged at the distal end of a cylindrical shaft which in the servicestate is oriented radially to the pipeline and extends at leastsectionally into the pipeline, such that the reaction chamber in theservice state is located completely within the pipeline, and such thatboth reactant lines extend from outside the pipeline longitudinallythrough the shaft toward the reaction chamber.

The invention accordingly provides an arrangement for the addition ofchlorine dioxide to a water-carrying pipeline, comprising a cylindricalreaction chamber and two reactant lines which open out into the reactionchamber and via which two reactants can be conveyed separately, fromoutside the pipeline, into the reaction chamber, the reaction chamberbeing provided with an exit hole which allows the exit of chlorinedioxide, formed from the reactants in the reaction chamber, into thewater carried by the pipeline, and the axis of the exit hole in theservice state being oriented in the direction of the longitudinal axisof the pipeline, wherein the reaction chamber is arranged at the distalend of a cylindrical shaft which in the service state is orientedradially to the pipeline and extends at least sectionally into thepipeline, such that the reaction chamber in the service state is locatedcompletely within the pipeline, and such that both reactant lines extendfrom outside the pipeline longitudinally through the shaft toward thereaction chamber.

The invention is therefore notable in particular for the shaft, which isarranged radially to the pipeline and which extends into said pipeline.Within the shaft there is no synthesis of chlorine dioxide; thatsynthesis takes place exclusively within the reaction chamber which isarranged at the distal end of the shaft. The shaft therefore initiallyfulfils the function of positioning the reaction chamber within thepipeline, so that in an accident scenario the chlorine dioxide is takenoff in dilution by the water carried within the pipeline. Furthermore,the shaft surrounds the two reactant lines, so that the reactants can beneatly conveyed separately from one another into the reaction chamber,only intermixing therein and reacting to form chlorine dioxide. With thearrangement according to the invention, therefore, the chlorine dioxideis always produced within the pipeline. By virtue of its cylindricalform, the shaft has a streamlined shape. Lastly, the shaft protects thereactant lines from damage, thereby further enhancing the safety of theunit.

In one preferred embodiment of the invention, the dimensions of shaftand reaction chamber are such that the axis of the exit hole in theservice state extends coaxially with the longitudinal axis of thepipeline. This means that chlorine dioxide exits centrally in thepipeline and thus enables outstanding mixing with the water flowingwithin the pipeline.

In one preferred embodiment of the invention, the reaction chamber isfastened detachably on the shaft, in particular by means of a screwconnection. This permits the simple construction of a sequence ofdifferent arrangements with different performance classes, which will beelucidated in more detail later on.

Preferably, the reaction chamber, like the shaft, possesses acylindrical form, is arranged coaxially with said shaft, and has thesame outer diameter as said shaft; accordingly, with the reactionchamber mounted, the cylindrical form of the shaft is continued onto thedistal end of the reaction chamber with no changes in cross section.This embodiment results in low hydraulic resistance.

In one preferred embodiment, the reaction chamber not only has acylindrical outer form but also encloses a cylindrical reaction volumewhich is in contact with the surroundings exclusively via the tworeactant lines and via the exit hole, the two reactant lines opening outat a distance from one another on the proximal end face of the reactionchamber, and the exit hole being made in the shell of the reactionchamber, with the axis of the exit hole being arranged perpendicularlyto the axes of the outlets of the reactant lines, but not intersectingthese axes.

This design of the reaction chamber leads to outstanding intermixing ofthe reactants within the reaction chamber, meaning that the reactionproceeds rapidly. The low residence times associated with this permit asmall reaction volume, making the reactor less expensive and generatinga reduced flow resistance.

In one particularly preferred development, the exit hole should bearranged as close as possible to the outlets of the reactant lines, atleast in the proximal half of the reaction volume, when the entirereaction volume enclosed by the reaction chamber is conceptually dividedtransversely into a distal half and a proximal half.

As already mentioned, during the operation of a chlorine dioxide reactoraccording to the hydrochloric acid/chlorite process, there is,inherently, co-production of sodium chloride, which under amphorousoperational conditions causes the reactor to salt up.

Surprisingly, in operation according to the hydrochloric acid/chloriteprocess, the arrangement configured in accordance with the inventionshows no salt deposits at all if the ratio of the hourly generated massof chlorine dioxide (M) in grams to the cross section (Q) of the exithole in mm² is governed by the following relation:

(30 g/h/mm²)<M/Q<(60 g/h/mm²)

if the hole cross section Q is selected too small in relation to theproduction volume M (M/Q>60 g/h/mm²), the reaction chamber becomesclogged. If, alternatively, the hole cross section is dimensioned toogenerously (M/Q<30 g/h/mm²), the water flowing through the pipelinewashes out the reaction chamber and, in so doing, flushes out unreactedreactant. The conversion rate of the reaction and hence the efficientuse of resources are diminished as a result.

As already mentioned, by combining a shaft with different screw-onreaction chambers, it is possible to set up a sequential construction ofarrangements according to the invention, this construction entailing asmall number of parts. The invention accordingly further provides asequential construction comprising at least two arrangements accordingto the invention, with screw-connected reaction chambers, where the twoarrangements have different reaction volumes and their shafts areidentical.

Since within the sequential construction it is then necessary only tovary the reaction volume and possibly the cross section of the exit holeas well—the reactant lines can be kept constant—it is appropriate toconstruct the sequential construction on a uniform shaft, which to varythe conversion performance is combined with different reaction chambers.In this way, the number of parts within the sequential construction issignificantly reduced, thereby significantly lowering the productioncosts. A further possibility is to convert an existing reactor into ahigher performance class by changing over the reaction chamber.

The sequential construction preferably has not just two arrangements intwo performance classes, but instead a greater number of performancestages, such as four or five, for example.

Additionally provided by the invention, furthermore, is the combinationof a water-carrying line with the arrangement according to theinvention, where the pipeline has a pipe section within which thepipeline runs linearly and on which the pipeline is provided with a deadwater zone which extends radially relative to the pipe section, and intowhich the shaft of the arrangement has been introduced coaxially, suchthat the exit hole is located centrally in the pipe section and its axisis turned coaxially with the longitudinal axis of the pipe section. Inthis united construction of pipeline and reactor, there is noaccumulation of salt at the product exit point, and the flow resistanceof the shaft protruding into the pipeline, with the reaction chambermounted, is comparatively low.

Further provided by the invention is the use of the arrangementdescribed for the treatment of water flowing in the pipeline withchlorine dioxide which has been synthesized from the reactants in thereaction chamber. The chlorine dioxide is synthesized more particularlyby the sodium chlorite/hydrochloric acid process. The treatment ispreferably a biocidal treatment, in other words the killing ofmicroorganisms living in the water, with ClO₂. Microorganisms are, inparticular, bacteria, viruses, fungi, germs, spores, algae or microbes.The killing of the microorganisms, in other words the disinfection ofthe water, is untaken from an industrial motivation in the case, forexample, of the treatment of cooling waters, or alternatively on medicalor veterinary grounds, as in the case of the treatment of drinking wateror wash water in the case of interventions in the animal or human body.

The invention is now to be elucidated in more detail by means ofexemplary embodiments. For this purpose

FIG. 1: shows a first embodiment of the shaft, in a side view;

FIG. 2: shows a reaction chamber for a large conversion volume;

FIG. 3: shows the shaft from FIG. 1, in plan view;

FIG. 4: shows a reaction chamber for smaller conversions;

FIG. 5: shows a second shaft with flange and screwed-on reactionchamber;

FIG. 6: installation scenario, frontal;

FIG. 7 a: exit position 180° relative to the reactant lines;

FIG. 7 b: exit position 90° relative to the reactant lines;

FIG. 8: effect of the 180° exit position on the conversion rate;

FIG. 9: effect of the 90° exit position on the conversion rate;

FIG. 10: effect of the size of the exit opening on the conversion rate.

FIG. 1 shows the side view of a first embodiment of the shaft 1. Theshaft 1 essentially comprises a solid cylinder of PTFE in which tworeactant lines 2 a, 2 b have been made in the longitudinal direction.The reactant lines 2 a, 2 b extend over almost the entire length of theshaft 1, from its proximal end to its distal end. Over almost its entirelength, the shaft 1 has a cylindrical form with an outer diameter D.Only at its proximal end is the shaft 1 designed with a hammerheadshape, and at that point it possesses two coupling sleeves 3 a, 3 b,with one of the two reactant lines 2 a, 2 b opening out into each ofthese sleeves. The purpose of the coupling sleeves 3 a, 3 b is to beconnected to metering pumps, not shown, via which the reactants forsynthesizing the chlorine dioxide are conveyed into the arrangement. Ifthe arrangement is operated according to the hydrochloric acid/chloriteprocess, hydrochloric acid, for example, is conveyed into the shaft viathe coupling sleeve 3 a, while sodium chlorite is introduced via thecoupling sleeve 3 b. In the present example, the coupling sleeves 3 a, 3b and the reactant lines 2 a, 2 b are completely identical inconfiguration, and consequently it is immaterial which reactant isconnected to which coupling. All that is important is that at this pointin time the two reactants do not intermix, but are instead conveyedseparately from one another through the shaft 1 in the direction of itsdistal end. For this purpose, the two reactant lines 2 a, 2 b arearranged separately from one another in the shaft 1, and extend from thehammerhead at the proximal end, in parallel, to the distal end of theshaft 1, at which an external thread 4 has been applied. At the end ofthe external thread 4, the reactant lines 2 a, 2 b open out from theproximal end of the shaft 1. Where the arrangement is operated with adifferent chemistry, it may also be advantageous to provide differentline cross sections, in turn necessitating exact coupling. In order toprevent incorrect coupling, it is advantageous to configure both linesidentically and to select a simple chemistry.

The external thread 4 is intended for screw connection of the shaft 1 tothe cylindrical reaction chamber 5 shown in FIG. 2. For this purpose,the reaction chamber 5 has an internal thread 6, by which it is screwedonto the external thread 4 of the shaft 1. Since the outer diameter D ofthe reaction chamber matches the shaft diameter D, there are no externalcross-sectional changes at the transition between shaft and reactionchamber, which would give rise to eddies in the pipeline.

In the screwed-on state, the reaction chamber 5 encloses a reactionspace, shown with dashed lines in drawing 2, with the reaction volume V.Immediately after the end of the internal thread 6, an exit hole 7 withcross section Q has been made in the shell of the reaction chamber 5. Inthe screwed-on state, the reaction volume V is in contact with theenvironment exclusively via the exit hole 7 and via the distal outletsof the two reactant lines 2 a and 2 b. In operation, the two reactantsare passed into the reaction chamber 5 via the coupling sleeves 3 a, 3 band along the reactant lines 2 a and 2 b, and do not intermix until theyreach said chamber 5. The reaction of the products to form chlorinedioxide therefore takes place within the reaction volume V. The chlorinedioxide produced by reaction is displaced from the reaction volume V bythe continued conveying of reactants, and exits the reaction chamberthrough the hole 7. The dimensions of the reaction volume V are suchthat the residence time of the reactants within the reaction chamberamounts to around 5 seconds.

FIG. 4 shows an alternative embodiment of the reaction chamber 5, whichdiffers in its reaction volume V from the reaction chamber shown in FIG.2. This difference is achieved by the length of the reaction space beingless and the internal diameter of the reaction chamber as well beingsomewhat smaller. The cross section Q of the hole 7 is greater than inthe case of the embodiment in FIG. 2. Since, however, the diameter ofthe internal thread 6 of the reaction chamber 5 shown in FIG. 4 alsomatches the external thread 4 of the shaft 1 shown in FIG. 1, it ispossible for the reaction chamber in FIG. 4 to be screwed onto the shaftof FIG. 1 without a discontinuity in diameter. As a result of reductionof the volume flow rates of the reactants conveyed in, a residence timeof five seconds is again established; the formula which applies here isT=V/W, where T stands for the residence time, V for the reaction volumeand W for the volume flow rate of the two reactants into the chamber.Since the reaction volume has been made smaller, the volume flow ratesof reactants must be reduced accordingly in order to maintain the sameresidence time.

The result achieved through combination of the reaction chamber shown inFIG. 4 with the shaft shown in FIG. 1 is a reactor which has a muchlower synthesis performance than the combination of the shaft from FIG.1 with the chamber from FIG. 2. The combination from FIG. 1 and FIG. 2is designed for a conversion rate of 2000 g of chlorine dioxide perhour, whereas the combination from FIG. 1 and FIG. 4 is designed forchlorine dioxide production of only 200 g per hour.

It is easy to see that by virtue of the screw connection 4, 6 betweenreaction chamber 5 and shaft 1, it is possible, using a small number ofparts, to construct a sequence of reactors which cover differentperformance ranges. In this case, in practice, a greater number ofperformance stages will be provided than the two nominal sizes shown inthe examples.

FIG. 5 shows an alternative embodiment of the shaft 1, which ischaracterized by a flange 8 arranged beneath the coupling sleeves 3 a, 3b. The flange 8 serves to fasten the shaft to a dead water zone on thepipeline, in which the water to be treated flows. This is elucidatedagain in detail in FIG. 6. The rest of the construction of the shaft 1shown in FIG. 5 corresponds to that from FIG. 1. The external thread 4has the same size as the shaft in FIG. 1, and so it is possible tocombine both reaction chambers from FIG. 2 and FIG. 4 with the shaft inFIG. 5. A difference relative to the first embodiment in FIG. 1 is thatthe shaft length is somewhat less. Different shaft lengths arenecessary, however, to adapt the arrangement to different line crosssections of the water-carrying pipelines.

FIG. 6 now shows the installation scenario of the arrangement of theinvention. A pipeline 9 runs linearly, that is to say with no curvature,over the section shown. The flow direction of the water to be treated istherefore directed out of the plane of the drawing in FIG. 6, toward theviewer. Within the linear section shown, the pipeline 9 has a dead waterzone 10 which extends continuously radially from the pipeline 9. Thedead water zone 10 has a much smaller diameter than the diameter of thepipeline 9. With the reaction chamber 5 screwed on, the shaft 1 isinserted into the dead water zone 10. Fixing takes place via the flange8, located on the shaft, to a corresponding mating flange 11 on the deadwater zone 10. The flange screw connection necessary for this purpose isnot shown. Inserted between the dead water zone 10 and the shaft 1 is asealing element (likewise not shown), which prevents fluids escapingfrom the pipeline 9 or from the dead water zone 10 via the flangeconnection 8, 11. With the shaft inserted, the shaft 1, like the deadwater zone 10, extends radially relative to the longitudinal axis of thepipeline 9. The dimensions of the shaft length and reaction chamber hereare such that the exit hole 7 is located at the level of thelongitudinal axis of the pipeline 9. The chlorine dioxide flows out ofthe reaction chamber 5 in the flow direction of the water to be treated.The orientation of the axis of the exit hole 7 coaxially with thelongitudinal axis of the pipeline 9 in accordance with the invention,downstream, has proved ideal. The radial orientation of the shaft 1 tothe longitudinal axis of the pipeline, rotated by 90° relative to theprevious orientation, and its cylindrical form, which continues via thereaction chamber 5, is favourable from the standpoint of fluid dynamics.

In operation, one reactant is conveyed into the shaft via each sleeve (3a shown, 3 b facing away from the viewer in the section in FIG. 6, andtherefore not visible) separately, and flows through the reactant lines2 a, 2 b into the reaction chamber 5. Within the reaction volume V, thereactants undergo reaction to give chlorine dioxide and, after aresidence time of preferably five seconds, they leave the reactionchamber 5 through the exit opening 7. The highly concentrated chlorinedioxide then intermixes suddenly with the water H₂O that is arriving ina high-volume flow and which is conveyed through the pipeline 9.Downstream, the water treated with chlorine dioxide has a certainconcentration of ClO₂ that reliably kills microorganisms in the waterH₂O.

The entire shaft 1 and the reaction chamber 5 are manufactured whollyfrom PTFE. Both parts are turned or milled from the solid material.

Table 1 shows technical data for three embodiments of the arrangement indifferent performance classes, including the structural dimensions andoperational parameters necessary for maintaining the short residencetime.

TABLE 1 Structural sizes and operating data within a construction seriesStructural size I II III Maximum ClO₂ (g/h) 400 900 2000 generationcapacity M Volume flow rate HCl (l/h) 2.24 5 11.2 Volume flow rate (l/h)2.24 5 11.2 NaClO₂ Concentration HCl (%) 30 30 30 Concentration NaClO₂(%) 25 25 25 Molar ratio HCl:NaClO₂ (—) 2.4 to 3.4 2.4 to 3.4 2.4 to 3.4Reactor pressure/water (bar) 6 6 6 pressure difference Maximum pressure(bar) 9 9 9 of system Water temperature (° C.)  5 to 40  5 to 40  5 to40 Reactant lines diameter (mm) 4.5 4.5 4.5 Internal diameter of (mm) 2027 26 reaction chamber Length of reaction (mm) 31 36 65 chamber LReaction volume V (mm³) 9739 20 611 34 509 Residence time (s) 7.83 7.425.55 Exit hole diameter (mm) 4 4.5 7.5 Cross section of hole (mm²) 12.5715.90 44.18 for product exit Q Ratio M/Q (g/h/mm²) 32 57 45 Outerdiameter of (mm) 25 32 32 reaction chamber K

Experiment 1 Effect of Position of the Product Exit on the ConversionRate

In a series of experiments, a combination of pipeline and reactor asshown in FIG. 6 was investigated for the effect of the position of thehole (180° and 90°) on the conversion rate, with a hole diameter of 2 mmor 3 mm. In the case of the 180° position shown in FIG. 7 a, the axis ofthe hole points in the direction of the longitudinal axis of thepipeline; with the 90° position in FIG. 7 b, it is arranged transverselyto the pipe axis. By rotating the reaction chamber, therefore, it waseasily possible to compare the position of the exit opening at 180°(FIG. 7 a) with a reactor according to the invention (90°, FIG. 7 b).The results are shown in FIGS. 8 and 9.

TABLE 2 Parameters of the experiments shown in FIG. 8 Area PositionMolar ratio Residence of exit of exit Experiment (HCl:NaClO₂) time ØExit hole opening opening Yield 06.12.2011-2   3:1 5 sec. 2x 2 mm  6.3mm² 180° 97% 06.12.2011-3 3.1:1 5 sec. 2x 3 mm 14.1 mm² 180° 86%

Experiment 06.12.2011-2 was carried out using 2 mm holes. The yield wasapproximately 100% before the conversion collapses completely anddropped even to below 20%. This is probably attributable to lumps ofsalt which blocked the two holes.

Experiment 06.12.2011-3 was carried out using 3 mm holes. The conversionyield fluctuates between about 75%-about 90%

TABLE 3 Parameters of the experiments shown in FIG. 9 Area PositionMolar ratio Residence of exit of exit Experiment (HCl:NaClO₂) time ØExit hole opening opening Yield 06.12.2011-1 3.1:1 5 sec. 2x 2 mm  6.3mm² 90° 91% 06.12.2011-4 3.1:1 5 sec. 2x 3 mm 14.1 mm² 90° 77%

Experiment 06.12.2011-1 was carried out using 2 mm holes. The yieldfluctuated between about 80% to 100%.

Experiment 06.12.2011-4 was carried out using 3 mm holes. The yieldclimbs with fluctuation from about 40% to about 90%.

From the results it can be concluded that where possible the position ofthe exit opening should be made at 90°, i.e. transverse to thelongitudinal axis of the pipeline, since higher and more stableconversion rates can be expected.

Experiment 2 Effect of the Hole Diameter on the Conversion Rate

The intention was to investigate whether the size of the diameter of thehole for product exit in the arrangement shown in FIG. 6 has an effecton the conversion rate. The background to this is that a larger holediameter correlates with the possibility of more effectively dissipatingany possible pressure rise in the reactor interior and/or with thegreater ease of flushing salt from the reactor interior if such salt isformed. The reactor used had a production capacity of 2000 g/h.

TABLE 4 Parameters of the experiments shown in FIG. 10 Area PositionMolar ratio Residence of exit of exit Experiment (HCl:NaClO₂) time ØExit hole opening opening Yield 11.01.2012-1 3.1:1 5 sec. 1x 4.5 mm 15.9mm² 90° 96% 11.01.2012-2 2.9:1 5 sec. 1x 5.5 mm 23.7 mm² 90° 97%12.01.2012-1 2.7:1 5 sec. 1x   7 mm 38.5 mm² 90° 96%

In experiment 11.01.2012-1, the yield fluctuates between about 90% andabout 100%.

In experiment 11.01.2012-2, the yield fluctuates between about 90% andabout 100%.

In experiment 12.01.2012-1 the yield fluctuates between about 90% andabout 100%.

With this experiment, the fluctuations are less strongly pronounced thanin the other two experiments.

Experiment 2 shows that small holes can become clogged by salt, thatlarger holes improve gas removal and hence the conversion rate, and thatwater, if holes are too large, may wash out and/or dilute the reactorcontents, and that the conversion rate may collapse.

Experiment 3

The intention was to investigate the effect of the ratio of thecross-sectional area Q of the exit opening to the production performanceM of the reactor, and whether this ratio is suitable as a designvariable for a series with different reactor performance classes. Forthis purpose, conversion experiments were undertaken using differenthole cross sections and different generational performances; the molarratio of the reactants and the residence time, were not varied. Theresults are plotted in Table 5.

TABLE 5 Results of experiment on varying the Q/M ratio ExperimentGenerational Molar ratio Residence Number of Hole No. performance M(HCl/NaClO₂) time holes diameter Exit area Q Ratio Yield [—] g/h [—] s[—] mm mm² Q/M [%] 11.07.2012-2 2000 2.8:1 5 1 9 63.6 31 92 11.07.2012-1900 2.7:1 5 1 6 28.3 32 100 10.07.2012-1 400 2.7:1 5 1 4.5 15.9 25 8921.12.2011-3 900 2.7:1 5 1 4.5 15.9 57 97 11.01.2012-2 2000 2.9:1 5 15.5 23.8 84 97 12.01.2012-1 2000 2.7:1 5 1 7 38.5 52 96 25.01.2012-12000 2.6:1 5 1 5 19.6 102 88 25.01.2012-2 2000 2.6:1 5 1 5 19.6 102 5220.01.2012-1 2000 2.7:1 5 1 5 19.6 102 81 20.01.2012-2 2000 2.6:1 5 1 519.6 102 73 20.01.2012-3 2000 2.6:1 5 1 5 19.6 102 66 20.01.2012-4 20002.6:1 5 1 5 19.6 102 69 20.04.2012-1 2000 2.7:1 6 1 8 50.3 40 98

In the experiments set out in Table 5 it can be seen that highconversions above 90% are achieved more at a ratio of Q/M of between 30and 60 than outside this range.

LIST OF REFERENCE CHARACTERS

-   1 shaft-   2 a first reactant line-   2 b second reactant line-   3 a first coupling sleeve (HCl)-   3 b second coupling sleeve (NaCl)-   4 external thread-   5 reaction chamber-   6 internal thread-   7 exit hole-   8 flange-   9 pipeline-   10 dead water zone-   11 meeting flange-   D outer diameter of reaction chamber and shaft-   M hourly generated mass of chlorine dioxide-   Q cross section of exit hole-   V reaction volume

1. An arrangement for the addition of chlorine dioxide to awater-carrying pipeline having a longitudinal axis, comprising: acylindrical shaft extending at least sectionally into the pipeline,directed radially to the pipe-line and having a reaction chamber at adistal end oriented such that the reaction chamber is within thepipeline; wherein within the cylindrical shaft are two separate reactantlines which run longitudinally through the shaft from outside the waterpipeline into the reaction chamber, the reaction chamber comprises anexit hole having an axis, which in a service state is oriented in thedirection of the longitudinal axis of the pipeline and in a flowdirection of the water, and further wherein chlorine dioxide obtained byreaction of reactants in the reaction chamber passes through the exithole into water in the pipeline.
 2. The arrangement according to claim1, wherein the axis of the exit hole in the service state is arrangedcoaxially with the longitudinal axis of the pipeline.
 3. The arrangementaccording to claim 1, wherein the reaction chamber is fasteneddetachably on the shaft.
 4. The arrangement according to claim 3,wherein the reaction chamber is fastened to the shaft by a screwconnection.
 5. The arrangement according to claim 1, wherein thereaction chamber and shaft are oriented coaxially with one another, andan outer diameter of the reaction chamber is equal to an outer diameterof the shaft.
 6. The arrangement according to claim 5, wherein acylindrical reaction volume of the reaction chamber is accessibleexclusively via the two reactant lines and via the exit hole, the tworeactant lines open in the reaction chamber at a distance from oneanother on the proximal end face of the reaction chamber, and the exithole is in the shell of the reaction chamber, with the axis of the exithole arranged perpendicularly to axes of the outlets of the reactantlines, but not intersecting the axes of the outlets.
 7. The arrangementaccording to claim 6, wherein when the reaction volume is dividedtransversely into a distal half and a proximal half, the exit hole islocated in the proximal half of the reaction volume.
 8. The arrangementaccording to claim 1, wherein a ratio M/Q of hourly generated mass ofchlorine dioxide (M) in grams to a cross-sectional area (Q) of the exithole in mm² is from greater than 30 g/h/mm² to less than 60 g/h/mm². 9.A type series comprising at least two of the arrangement according toclaim 3, wherein the reaction volume of each of the at least twoarrangements are different and the shafts of each are identical.
 10. Awater-carrying pipeline, comprising: a pipe section within which thepipeline runs linearly and on which the pipeline comprises a dead waterzone which extends radially to the pipe section; and the arrangementaccording to claim 1 wherein the shaft of the arrangement is coaxial tothe pipeline, and such that the exit hole is located centrally in thepipe section and its axis is arranged coaxially with the longitudinalaxis of the pipeline on the pipe section.
 11. A method to treat water,the method comprising: passing the water through a pipeline comprisingat least one arrangement according to claim 1; supplying reactants whichreact to yield chlorine dioxide separately through the reactant lines tothe reaction chamber; reacting the reactants in the reaction chamber toobtain chlorine dioxide; and passing the chlorine dioxide to the waterin the pipeline through the exit hole.
 12. The method according to claim11, wherein the reactants which react in the reaction chamber are sodiumchlorite and hydrochloric acid.
 13. The method according to claim 11,wherein a ratio M/Q of hourly generated mass of chlorine dioxide (M) ingrams to a cross-sectional area (Q) of the exit hole in mm² is fromgreater than 30 g/h/mm² to less than 60 g/h/mm².
 14. The methodaccording to claim 11, wherein the treatment of the water with thechlorine dioxide comprises killing microorganisms living in the water.15. The method according to claim 14, wherein the microorganism kill isdetermined on the basis of a medical or a veterinary indication.